Dynamic balancing apparatus

ABSTRACT

A dynamic balancing apparatus for a rotary member, such as a grinding wheel, supported for rotation on a spindle journaled in a spindle housing. The spindle housing is pivoted on a support for rocking movement under the control of a resilient restraining means. Balancing is effected by the release of self-adjusting weights operating in a raceway on the spindle adjacent the rotary member. After balancing, the housing is clamped tightly to the support.

United States Patent [191 Decker [54] DYNAMIC BALANCING APPARATUS [75]Inventor: Jacob Decker, Cincinnati, Ohio [73] Assignee: CincinnatiMilacron Inc., Cincin nati, Ohio [22] Filed: Nov. 17, 1971 [2]] Appl.N0.: 199,435

[52} U.S. Cl ..74/573, 51/169 [51] Int. Cl. ..F16f 15/32 [58] Field ofSearch ..74/573; 51/169 [56] References Cited UNITED STATES PATENTS2,142,021 12/1938 Ernst et al. ..74/573 X FOREIGN PATENTS ORAPPLICATIONS 136,214 2/1960 ULS.S.R...............'..

l............5l/l69 1451 May 8,1973

Primary Examiner-Milton Kaufman Assistant ExaminerF. D. ShoemakerAttorney-Howard T. Keiser et al.

[57] ABSTRACT A dynamic balancing apparatus for a rotary member, such asa grinding wheel, supported for rotation on a spindle journaled in aspindle housing. The spindle housing is pivoted on a support for rockingmovement under the control of a resilient restraining means. Balancingis effected by the release of self-adjusting weights operating in araceway on the spindle adjacent the rotary member. After balancing, thehousing is clamped tightly to the support.

8 Claims, 5 Drawing Figures DYNAMIC BALANCING APPARATUS BACKGROUND OFTHE INVENTION This invention relates to a dynamic balancing apparatus ofthe type in which self-adjusting weights are supported for concentricmovement with respect to the geometric axis of the rotary member andassume, during rotation, positions which are such as to correct anyout-of-balance condition of the member. This balancing action dependsfor its operation on a pivotal support for the spindle at a point remotefrom the rotary member to rotate about its axis of mass rather thanabout its geometric axis. A balancing device of this type is shown inUS. Pat. No. 2,507,558 to Dall et al. dated May 16, 1950. In the deviceshown in the patent, the spindle bearing adjacent the grinding wheel isresiliently supported on spring rods while the bearing adjacent thedrive pulley acts as a pivot and permits gyration of the free end of thespindle thereabout. When the grinding wheel is rotated above itscritical speed, it will tend to rotate about its center of mass, and thebalancing weights, or balls, will distribute themselves about the axisof the spindle in such a way as to reestablish rotation of thespindle-wheel combination about its geometric axis. This mechanism hasper formed very satisfactorily but is somewhat complicated and expensiveto manufacture because of the flexible supporting and clampingarrangement required for the front bearing.

SUMMARY OF THE INVENTION The present invention has for its object theprovision of a dynamic balancing mechanism for a rotary member, such asa grinding wheel, which is just as effective as the mechanism shown inthe above-mentioned patent, but which is less complicated and lessexpensive to construct. To this end, the spindle bearings are fixedlymounted in the spindle housing and the housing itself is arranged topivot about a point remote from the rotary member. Oscillatory movementof the housing about the pivot, is yieldably restrained by a resilientsupport means to allow the rotary member to rotate about its axis ofmass. Balancing weights of the type disclosed in the afore-mentio'nedpatent are permitted to seek positions in which they correct theoutof-balance condition after which they are clamped. To

provide a rigid support for the rotary member, means is provided forclamping the spindle housing to its support so as to render it immobilethereon after the balancing has been effected.

DESCRIPTION OF THE DRAWINGS view taken along DESCRIPTION OF THEPREFERRED EMBODIMENT The improved form of dynamic balancing mechanism isshown herein in connection with a grinding machine the details of whichare not set forth since they form no part of the present invention. Inthe mechanism shown, a grinding wheel 10 (FIGS. I and 2) is mounted on aflange 11 provided on one end of a spindle 12. The spindle is journaledin a spindle housing 13 by means of front and rear bearings 14 and 15,respectively. Axial movement of the spindle is prevented by a thrustbearing 16 and a collar 17 located on opposite sides of the bearing 14.Power for driving the spindle and the grinding wheel is supplied by amotor (not shown) which drives a pulley 18 on the spindle by means ofmultiple V-belts 19.

The spindle housing 13 is pivotally mounted on a support 25 by a shaft26 (FIG. 4) secured to the housing in the vicinity of the rear bearing15. The shaft is disposed with its axis normal to that of the spindleand permits oscillation of the housing in a plane parallel to the axisof the spindle. The shaft is provided with a flange 2'7 and a tenon 28which are received in corresponding bores provided therefor in thehousing 13. The shaft 26 is secured to the housing 13 by screws 29passing through the flange 27 and into the body of the housing. A bore24 is provided in the support 25 for receiving needle bearings 30 whichjournal the shaft in the support.

At its forward end, that is, the end adjacent the grinding wheel 10, thehousing 13 is provided with a bore for receiving one end of a spring rod31 which is secured therein by a set screw 32. The rod 31 passes throughan aperture 33 in the wall of support 25 and is slidably received in abushing 34 rigidly mounted in a web 39 formed in the support 25.. Thus,pivotal move ment of the housing 13 about the pivot shaft 26 isresiliently restrained by flexing of the rod 31. With the end of thehousing 13 adjacent the grinding wheel free to oscillate about the axisof the pivot shaft 26 when the wheel is rotated above its criticalspeed, balance of the wheel may be. achieved by releasing a plurality ofweights 35 (FIG. 2) riding in a raceway 36 concentrically disposed inthe flange ll of the spindle. After balancing has been effected, theweights 35 may be clamped in their adjusted positions'by a flange 37 onthe end of plunger 38 which is axially 'slidable within the spindle 12.This portion of the apparatus may be constructed in the manner describedin U.S. Patent No. 2,507,55ti wherein the plunger 38 is normally urgedinto clamping position by a spring and is released by the application ofhydraulic pressure applied to the opposite end thereof within thespindle. As described in the patent, the balancing weightsmay take theform of steel balls there being three such weights in the preferredembodiment.

After balance has been achieved, it isdesirable to clamp the housing 13against movement relative to the support 25 so as to provide a rigidbase for the grinding wheel. For this purpose clamp means are providedat each end of the housing, the clamp means at the forward end takingthe form, of a clamp dog 42 (FIG. 4) having a tail portion 43 rockablysupported in a recess formed in a block 44 secured to the support 25. Atits opposite end the dog is provided with a beveled clamp face 45 whichis adapted to bear against a corresponding surface provided on theunderside of the housing. Situated on the upper side of the housingopposite the dog 42 is a fixed clamp dog 46 which is secured by screws47 to the support and has a beveled clamp face 48 engaging acorresponding surface on the housing.

Activation of the clamp dog 42 is effected by a piston 49 having a rod50 connected by a link 51 to the dog 42. The piston is urged toward theright or into clamping position by means of a series of Bellevillewashers 52 acting between the piston and the end of a guide bushing 53for the rod 50. Movement of the piston to the left, or to the unclampedposition, is effected by hydraulic pressure applied to the piston by ahydraulic intensifier 54. This device consists of a large piston 55.

and a small piston 56 which are constructed as a single unit and operatein unison within their respective cylinders. Accordingly, when hydraulicpressure is supplied to the line 57, the piston 55 will move toward theleft whereby the small piston 56 will compress the hydraulic fluidcontained in the cylinder containing piston 49 and cause the piston tobe moved toward the left. Thereby, the dog 42 will be released and theface 48 will move away from the fixed dog 46 due to the unbalancedweight of the forward end of the housing which will turn on the pivotagainst the bias of the spring rod 31. Make-up fluid for the cylindersis supplied through a line 58 and a check valve 59 as shown in FIG. 4.

The pulley end of the housing 13 is adapted to be clamped to the support25 by a similar mechanism applied to the pivot shaft 26. Again referringto FIG. 4, the distal end of the pivot shaft is adapted to receive athrust bearing 62 which is subjected to axial pressure by Bellevillewashers 63, held in compression by a lock nut 64 threaded on the end ofthe shaft. Thus the pivot shaft and the housing 13 secured thereto arenormally urged toward the right as viewed in FIG. 4 so as to urge thepulley end of the housing into clamping engagement with the support.This pressure or force may be relieved by'the selective application ofhydraulic fluid under pressure to a line 65 connected to a cylindercontaining a piston 66 having a rod 67 adapted to bear against the endof the pivot shaft 26.

To insure free swinging movement of the housing 13 in the vicinity ofthe spring rod 31, provision is made for selectively moving the rodtoward the left, as viewed in FIG. 3, through a small distancesufficient to insure clearance between the housing and the support 25.The mechanism for accomplishing this is best shown in FIG. 2 andincludes a lever 67 pivoted on the support at 68 and having one armthereof bearing against the inner end of the rod 31. The other end ofthe lever is adapted to be actuated by a piston 69 operating within acylinder provided therefor in the web 39. When fluid pressure is appliedto the cylinder through a line 70, the piston 69 will rock the leverabout its pivot and force the rod 31 outwardly to the extent permittedby a limit stop 71. The axial movement of the spring rod 31 within thebushing 34 need only be enough to prevent frictional contact between theadjoining surfaces of the housing 13 and support 25. A rod travel offrom 0.003 0.005 inches is normally sufficient to accomplish this.

A modified form of spindle drive mechanism is shown in FIG. 5 of thedrawings. In this embodiment, a torque coupling is interposed betweenthe belt pulley and the spindle 12 so as to remove the influence of thebelt tension from the pivoting action of the spindle housing 13 aboutthe shaft 26 during balancing operations. A driving motor (not shown)drives a pulley 76 by multiple V-belts 77 as before. In this case,however, the pulley 76 is mounted on the outer end of a stub shaft 78which is journaled in bearings 79 mounted in a bracket 80 secured to thesupport 25. The stub shaft 78 is secured to the input member of coupling75 which, as shown, may take the form of the well-known Oldham coupling.The output member of the coupling is connected to the spindle 12 todrive the same as required. Inasmuch as the location of the coupling isclosely adjacent the pivot axis of the housing 13 on its support, therewill be a minimum of interference by the drive with the pivoting actionof the housing.

The balancing apparatus of the present invention operates as follows:Whenever it becomes necessary to balance the rotary member 10, theclamping means are released and the member 10 is driven at a speed suchthat the period of rotation thereof exceeds the natural frequency of thegrinding wheel spindle housing combination supported on the spring rod31. The balancing weights 35 are then released to allow them to move topositions in which they serve to correct any imbalance of the rotarymember. The weights are then clamped in their adjusted positions by theplunger 38 (H6. 2) after which the spindle housing 13 is clamped to thesupport 25 by relieving the pressure applied to the hydraulic fluid inlines 57, 65 and 70. The rotary member 10 is now balanced and themachine is ready to resume operation.

While the apparatus herein shown and described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this particular form of apparatus and that changes maybe made therein without departing from the scope of the invention.

What is claimed is:

1. Apparatus for dynamically balancing a rotary member mounted on theend of a spindle comprising a housing; journal means in said housing forsupporting said spindle for rotation therein ;,a support;

means to pivot said housing on said support for rotation about an axiswhich is disposed normal to the axis of said spindle and located at apoint remote from said rotary member;

resilient means for restraining pivotal movement of said housing aboutthe axis of said pivot means;

a circular raceway provided on said spindle adjacent the rotary member;and

a plurality of self-adjustable weights adapted to roll in said racewayduring rotation of said spindle and to assume such positions therein asto correct any imbalance of the rotary member.

2. The balancing apparatus of claim 1, including selectively operablemeans for clamping said housing to said support after balance has beeneffected.

3. The balance device of claim 2, wherein said resilient means comprisesa spring rod having one end mounted in said support and the other endmounted in said housing.

6. The balancing device of claim 1 including a power drive means forsaid spindle, and a torque coupling between said power drive means andsaid spindle.

7. The balancing device of claim 6 wherein the axis of the pivot forsaid housing intersects the axis of said spindle.

8. The balancing device of claim 7 wherein said torque coupling issituated adjacent to the point of intersection of the pivot and spindleaxes.

1. Apparatus for dynamically balancing a rotary member mounted on theend of a spindle comprising a housing; journal means in said housing forsupporting said spindle for rotation therein; a support; means to pivotsaid housing on said support for rotation about an axis which isdisposed normal to the axis of said spindle and located at a pointremote from said rotary member; resilient means for restraining pivotalmovement of said housing about the axis of said pivot means; a circularraceway provided on said spindle adjacent the rotary member; and aplurality of self-adjustable weights adapted to roll in said racewayduring rotation of said spindle and to assume such positions therein asto correct any imbalance of the rotary member.
 2. The balancingapparatus of claim 1, including selectively operable means for clampingsaid housing to said support after balance has been effected.
 3. Thebalance device of claim 2, wherein said resilient means comprises aspring rod having one end mounted in said support and the other endmounted in said housing.
 4. The balancing device for claim 3 includingselectively operable means for producing limited axial movement of saidspring rod to move said spindle housing away from said support duringbalancing operations.
 5. The balancing device of claim 2 wherein saidpivot means includes an axially movable shaft, and said clamping meansincludes an actuating mechanism for moving said shaft axially to engagesaid housing with said support.
 6. The balancing device of claim 1including a power drive means for said spindle, and a torque couplingbetween said power drive means and said spindle.
 7. The balancing deviceof claim 6 wherein the axis of the pivot for said housing intersects theaxis of said spindle.
 8. The balancing device of claim 7 wherein saidtorque coupling is situated adjacent to the point of intersection of thepivot and spindle axes.